Objects to be measured are various in types, and require their own measurement apparatuses to fit their individual measurement circumstances. In other words, measurement has been desired to deal with various measuring objects, not just sound and vibration but also temperature, humidity, pressure, and the like.
Techniques for measuring sound, noise, and the like are disclosed (see, for example, Patent Document 1: JP-A-2002-188953, Patent Document 2: JP-A-2006-64393, and Patent Document 3: JP-A-2010-78369). The technique according to Patent Document 1 is to transmit actual sound (noise) when a noise level exceeds a control level. Specifically, the noise level of noise can be measured with a microphone and a sound level meter. If the noise level is greater than a control level, it establishes a call with PHS (Personal Handyphone System) and allows an operator to hear the actual sound through the PHS.
Patent Document 2 discloses a system for measuring acoustic characteristics, which is configured to accurately measure the acoustic characteristics of a space such as a hall or a stadium. The grasping of acoustic characteristics is an important factor not just when music is played but also when clear announcement is desired.
Moreover, Patent Document 3 discloses an environmental data collecting/analyzing apparatus configured to collect and analyze a particular environmental data signal for noise or vibration and display the data on the printed paper or screen. According to Patent Document 3, the attribute of the graph line is made different to enable the visual recognition of the environmental data signal that is not to be measured. This facilitates the analysis of the measurement data for the noise or vibration, and the object to be measured and the object not to be measured can be easily distinguished.
As disclosed in Patent Documents above, various measurement circumstances are assumed generally in the measurement of the sound and vibration. As the examples, the traffic noise on the road and the noise from the railway, the measurement of the sound insulation performance, the measurement of the insulation of an automobile, and the measurement of the noise and vibration at the construction site are given.
In these cases, there are various pieces of data desired to be obtained at the measurement and various measurement locations depending on the measurement circumstances. When the measurement circumstances vary, various problems occur as below.    (1) In the case of transmitting measurement data wirelessly, there are possibilities that the measurement data are lost. The wireless communication causes a trouble more often than the wired communication. Moreover, disconnection may happen in the middle of the communication. If the measurement data are lost (if the measurement data have become deficient) in the middle of wireless communication, the reliability of the measurement is deteriorated. When the retransmission of the measurement data is repeatedly requested, the communication speed fails to follow the accumulation of the measurement data, in which case a measurer cannot know the current measurement data and information in the measurement.    (2) If the measurement data are wirelessly transmitted with the operation of the battery, a problem of the consumption power occurs. That is to say, if the measurement data are obtained remotely without the man power, the measurement data are continuously transmitted wirelessly. This increases the consumption power, which results in that the battery is changed more frequently. Moreover, the stand-by time may be long if the measurement is conducted not continuously but intermittently after the installation of the measurement device and the sensor.    (3) In the current technique, the device for processing a plurality of (three or more) channel signals in real time is large-scaled. When the device is large-scaled, the size, the weight, the consumption power (battery life), and the cost of the device are adversely affected.    (4) In the use of a plurality of measurement devices, if the measurement devices conduct measurement separately, the measurement start time cannot be synchronized. Therefore, the uniform process in regard to the time synchronization is impossible. Unless the uniform process is performed, the measurement data obtained by the measurement is not uniform. This results in a problem that the work efficiency of the operator in the subsequent work is deteriorated.
In view of the background as above, a technique has been desired that can flexibly deal with the loss of the data in the wireless communication. Moreover, a technique has been desired that can reduce the power consumption in the use of the wireless communication. Additionally, a technique has been desired that can effectively use the hardware resources. Furthermore, a technique has been desired that can manage a plurality of measurement devices efficiently.